Add endmarks to the end of a paragraph

I’m building out a blog and our design specs have us adding an “endmark” to the end of the article inline with the text (see screenshot). This would be easy for static text content, but these are obviously CMS-based articles, so I’m wondering how I might include this to go at the end of every article.

Would I need to use custom code to do this?

You can use CSS.
If you want it on all Rich text elements, you can do something like this;

div.w-richtext > *:last-child:after {
  content: "✦"; 
  color: red; 
  font-size: 20px; 
  margin-left: 5px; 
  vertical-align: baseline; 
  display: inline-block;
  top: 2px;
  position: relative;
}